@christiannewshighlights — depending on the theme, sometimes I have to drag a widget down to the lower right or lower left corner — as if off the screen — to get it to return to the group of unused widgets.
There are some bloggers on the forum all reporting the same thing. The inability to deleted widgets. All of you need staff help. Support hours are weekdays 9-5 PM and here’s the link http://wordpress.com/contact-support/